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Class 100 Gloucester RC&W 2-car DMUs

Floor and Roof


There was no separate underframe in the normal sense, but the weight of metal usually concentrated in the center longitudinals was spread over the whole width of the floor in the form of corrugated steel sections with the corrugations running longitudinally. This corrugated steel floor was cold rolled in 57 ft. lengths to eliminate the difficulty of matching and welding up joints across the coach, to sustain both the buffing and draw loads and to support passenger load between crossbars. The frame bolster, headstocks and buffing gear supporting structures were built up as unit assemblies. Again for the purposes of weight and strength, these units were fabricated from steel tube, sheet and plate, permitting the metal to be concentrated where it would do most work. Diffusion of buffing and draw loads into the corrugated steel floor was achieved by incorporating tubular longitudinals immediately behind the buffing and drawgear. In order to assist the diffusion of end loads into the corrugated floor, and to save weight, these tubular longitudinals were tapered in wall thickness, the thickness being greater at the two headstocks at the ends.

The first image shows the longitudinal corrugated steel sections forming the underframe.

sub assembly

The body end and the roof between cantrails were built up in much the same way as the standard British Railways coaches. With regard to the roof, it was felt that shear lag across the roof panels would reduce the effectiveness or incorporating extra framing or purlins, and therefore the cantrails were considered as the main load carrying members.

The second image shows a sub-assembly being formed in a jig

The various components comprising the whole of the structure were assembled to form a complete unit by a combination of riveting and welding designed to facilitate repairs being carried out on the frame without difficulty.

Many firms supplied the different metals required. The cold formed sections came from Metal Sections Ltd., and the Corten body panels from the Steel Co. of Wales Ltd. John Summers Ltd. supplied the roof sheets, and Deans & Sons (Yorkshire) Ltd. supplied the Cast Alloy doors.

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